Lateral adjustment means for radial arm saws

ABSTRACT

A lateral adjustment means for radial arm saws comprising an elongated traverse rod precisely axially adjustable in a longitudinal direction relative to the radial arm of a radial arm saw and means fixed to the carriage of a respective radial arm saw adapted to traverse said traverse rod longitudinally thereof and means for releasably fixing said last mentioned means to said traverse rod.

United States Patent Bower [54] LATERAL ADJUSTMENT MEANS FOR RADIAL ARMSAWS 211 App]. No.: 41,871

[ 51 May 23, 1972 2,047,887 7/ 1936 Robillard 33/164 R 3,023,792 3/ 1962Palmer et al. 143/6 C 3,192,816 7/1965 Zimmerman ..l43/6 A X PrimaryExaminer-Andrew R. J uhasz Assistant Examiner.lames F. CoanAttorney-William H. Dean ABSTRACT [22] A lateral adjustment means forradial arm Saws comprising an d S 6 C elongated traverse rod preciselyaxially adjustable in a longitu- 1 le 0 I 1 dinal direction relative tothe radial arm of a radial arm saw and means fixed to the carriage of arespective radial arm saw adapted to traverse said traverse rodlongitudinally thereof [56] Reta-anus Cited and means for releasablyfixing said last mentioned means to UNITED STATES PATENTS Said traverse2,989,094 6/1961 Panavas 143/6 A 7 Claims, 4 Drawing Figures I l a e I 1nmmnm -1- d a E a 2 PATENTEHHAY 2a 1972 3.664. 389

sum 1 or 2 INVENTOR N EXIL E. BOWER ATTORNEYS MTENTEDMAY 23 I912 3.664,389

sum 2 UF 2 I IE:

1 ICE: E

42 2 INVENTOR.

EXIL E. BOWER 50 44 48 ATTORNEYS LATERAL ADJUSTMENT MEANS FOR RADIAL ARMSAWS Conventional radial arm saws are provided with radial arms whichare supported in cantilever position so as to suspend a circular sawtherefrom. The circular saw is a power operated saw generally driven byan electric motor which is pivoted about a vertical axis in connectionwith a carriage which traverses longitudinally along the radial arm.Accordingly, the circular saw rotates on a horizontal axis and may bepivoted about a vertical axis in connection with the carriage in orderto dispose the rotating axis of the saw generally parallel to the radialarm or at right angles thereto for disposing the saw blade in a rippingposition or a respective cross-cut position as desired.

Conventional radial arm saws generally employ a manually operable meansfor fixing the carriage of a radial arm saw in certain adjusted positionrelative to the radial arm for holding the plane of the circular saw ina desired position for ripping boards or other material. It has beenfound in actual practice that the movement of the carriage relative tothe radial arm may be difiicult to control precisely in order to obtaina very accurate disposition of the plane of the saw relative to thework. Generally, the adjustment of the saw blade laterally relative tothe plane thereof, has been difficult due to the fact that the rollersof the carriage may contact particulate matter such as saw dust or thelike in the track on the radial arm and tend to cause the carriage andsaw blade to lunge an undesirable distance in a direction laterallyrelative to the plane of the circular saw blade. Accordingly, it hasbeen difficult precisely to adjust such saw blades on radial arm saws toa desired ripping position so that very accurate work may beaccomplished. The conventional means for holding a radial arm sawcarriage in a certain position with respect to the longitudinal axis ofthe radial arm comprises a conventional screwthreaded member which maybe manually tightened with respect to a fixture on the carriage so thata brake shoe may be locked against a corresponding brake shoe trackextending longitudinally along the radial arm.

Accordingly, operators of conventional radial arm saws wasteconsiderable time attempting to attain precise adjustment of thecircular saw blade of such saws laterally relative to the planes of saidblades for accomplishing precise ripping operations. This has not onlyutilized considerable time but also has been responsible for inaccuratework and possible damage to materials being ripped due to inaccuratelocation of the cut made by the saw.

In accordance with the present invention, a lateral adjustment means forradial arm saws permits the operator to make very accurate adjustmentsof the saw blade laterally relative to its plane of rotatation forattaining very accurate ripping operation of the saw with respect tomaterial being sawed thereby.

The invention employs a very simple mechanism which may be attached toconventional radial arm saws without undue alteration thereto and whichmay be very simply and easily used by the operator of a radial arm saw.Additionally, the invention does not hamper the normal operation of thecarriage of a radial arm saw relative to the radial arm during cross-cutsawing operations which are carried on by moving the carriage back andforth longitudinally the radial arm.

Specifically, the invention comprises a traverse rod having a meansholding it precisely in connection with the radial arm of a radial armsaw so that the traverse rod may be adjusted longitudinally of its axisin a very precise manner, and means on the carriage of the radial armsaw is adapted to be releasably fixed to the traverse rods at variousdesired positions to maintain an approximate disposition of the sawblade relative to a ripping position. The adjustment means of theinvention is then used to move the traverse rod precisely in a directionlongitudinally of its axis to thereby precisely move the saw blade in adirection laterally of its plane of rotation to an exact position forattaining accurate ripping operations thereof.

The conventional brake shoe actuating means of a radial arm saw may beutilized in accordance with the present invention for fixing the radialarm saw carriage relative to the traverse rod of the invention therebymaking the invention readily adaptable to conventional radial arm saws.

The invention comprises a very simple bracket which may be attached to aradial arm saw to hold a traverse rod of the invention in parallelrelation to the radial arm of a radial arm saw; the bracket beingadapted to provide a rotary bearing support for holding an internallyscrew-threaded adjusting sleeve precisely in position relative to thelongitudinal axis of the traverse rod and to permit rotation of thesleeve in relation to external screw threads on the rod so that the rodmay be precisely moved longitudinally of its axis by rotation of thesleeve. The sleeve is provided with dimensional calibrations which arerotatable relative to a stationary pointer so that precise movement ofthe traverse rod may be determined relative to the arm for preciselymoving the saw carriage of the conventional radial arm saw in adirection longitudinally of the radial arm thereof and to move the planeof a saw blade thereof into ripping position very precisely in adirection laterally of its plane of rotation. The invention permits anoperator to quickly fix the carriage of a radial arm saw in connectionwith the traverse rod of the invention and them permits the operator toadjust the rod precisely longitudinally of its axis to make a finiteadjustment of position of the radial arm saw blade laterally of itsplane of rotation.

Accordingly, it is an object of the invention to provide a very simpleand easily operable means for accurately adjusting radial arm saw bladesin a direction laterally of their axes of rotation when in rippingposition.

Another object of the invention is to provide a lateral adjustment meansfor radial arm saws which is very simple and easy to install onconventional radial arm saws.

Another object of the invention is to provide a novel lateral adjustmentfor radial arm saws which permits precise adjustment of the plane of acircular saw blade of a radial arm saw laterally of its plane ofrotation when in rip position and which does not hamper the normal useof the radial arm saw when in cross-cut position and when the carriagethereof is moved back and forth longitudinally along the radial arm.

Another object of the invention is to provide very a simple adjustmentmechanism for the traverse rod thereof which comprises a rotaryinternally screw-threaded sleeve conformingly containing an externallyscrew-threaded portion of the traverse rod of the invention; the sleevebeing rotatably mounted relative to the radial arm and axially parallelthereto and being restrained in a direction longitudinally of thetraverse rod so as to move the rod precisely in a longitudinal directionrelative to the radial arm when the internally screwthreaded sleeve isrotated relative to the traverse rod.

Other objects and advantages of the invention may be apparent from thefollowing specification, appended claims and accompanying drawings.

FIG. 1 is a fragmentary side elevational view of a radial arm sawshowing the circular saw blade thereof in ripping position and showingthe lateral adjustment means of the invention in connection therewith;

FIG. 2 is an enlarged fragmentary sectional view taken from the line 2-2of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view taken from the line 3-3of HG. l; and

FIG. 4 is an enlarged fragmentary sectional view taken from the line 4-4of FIG. 1.

As shown in FIG. 1 of the drawings, a radial arm saw is provided with acircular saw blade 10 mounted on a shaft 12 of a motor 14 in connectionwith a bracket 16 suspended from a carriage 18. The bracket 16 ispivotally movable about a vertical axis 20 in relation to the carriage18. The carriage 18 is provided with rollers 21 movable on a trackportion 22 of a radial arm 24 which is disposed generally in ahorizontal cantilever position. This arm 24 is mounted on a verticalstand 26 and the saw blade 10 is thus suspended to operate in closeproximity to a table top 28 upon which work may be sawed by the sawblade 10.

All of the foregoing equipment is substantially common to conventionalradial arm saws and the invention is particularly adapted to provide forprecise adjustment of the plane of the saw blade in directions parallelto the rotating axis thereof as indicated by the double-ended arrow A inFIG. 1 of the drawings and this adjustment as shown in FIG. 1 appliesparticularly to the saw blade 10 when in ripping position and when therotating axis thereof is disposed in substantially parallel relation tothe radial arm 24.

Disposed on the carriage 18 of the radial arm saw, is an upstandingclamp means 30 shown best in FIGS. 1 and 2 of the drawings. This clampmeans 30 may be the conventional member which contains the locking screwthat normally actuates the brake shoe in connection with the radial arm24 for holding the carriage 18 in juxtaposition longitudinally of theaxis of the radial arm 24.

In accordance with the present invention, however, the clamp means 30may be constructed as shown in FIG. 2 wherein this clamp means 30 isbifurcated into a pair of opposed clamp portions 32 and 34, the portion32 having a substantially semi-circular portion 36 directly opposed to asimilar portion 38 in the bifurcated portion 34. A traverse rod 40 isengaged between the semi-circular in cross section recessed portion 36and 38 so as to be clamped therebetween.

The clamp portion 32 is provided with an internally screwthreaded bore42 in which an externally screw-threaded portion 44 of a thumb screw 46is engaged. This screw 46 is provided with a manually engagable knob 48which contacts a hollow sleeve 50 and forces it against the clampportion 34 so as to cause the clamp portions 32 and 34 to firmly engageopposite sides of the traverse rod at the semi-circular in cross sectionrecessed portions 36 and 38 and to thereby fix the clamp means 30 on thetraverse rod 40 and to prevent rotation thereof relative to the carriage18 and the radial arm 24.

It will be seen that the traverse rod 40 is disposed in parallelrelation to the radial arm 24 and that when the screw 46 is released byturning it in a counter-clockwise direction that the clamp portions 32and 34 may be released from the traverse rod 40 and thereby allow theclamp means 30 to slidably move along the traverse rod 40 so thatmovement of the carriage 18 may be accomplished in the conventionalmanner for crosscut operations when the axis of the saw blade 10 isgenerally at right angles to the radial arm 24.

Accordingly, it will be seen that the clamp means 30 and the traverserod 40 do not impede normal operations of the radial arm saw.

The traverse rod 40 is provided with an externally screwthreaded portion52 as shown best in FIGS. 1 and 3 of the drawings. This externallyscrew-threaded portion 52 is engaged by internal screw threads 54 of ahollow sleeve 56 which is rotatably mounted in a bracket 58 fixed to theradial arm saw frame structure 60 by means of screws 62. The bracket 58is provided with an opening 64 in which the sleeve 56 is rotatablymounted. This sleeve 56 is provided with an enlarged diameter portion 66which abutts one side 68 of the bracket 58 to thereby provide forprecise disposition of the sleeve 56 in a direction longitudinally ofthe axis of the traverse rod 40 as will be hereinafter described indetail.

The sleeve 56 is provided with a manually engagable rotary knob 70 whichis fixed on the sleeve 56 and this knob abutts a washer 72 surroundingthe periphery 74 of the sleeve. The washer engages a compression spring76 which, at its opposite end, abutts another washer 78 which isrotatably slidable against a side 80 of the bracket which is opposite tothe side 86 precisely engaged by the enlarged diameter portion 66 of thesleeve 56.

The compression spring 76 acts as a detent to hold the washer 78 firmlyengaged with the side 80 of the bracket 58 and to thereby preventrotation of the sleeve 56 when in a desired adjusted position.

The periphery of the knob 70 is provided with dimensional calibrations82 which may be read adjacent to the end of a pointer 84 as shown inFIGS. 1 and 3 of the drawings. The

pointer 84 is fixed at 86 to the bracket 58 and when the knob 70 isrotated, the dimensional calibrations 82 are progressively movedrelative to the pointer 84 to indicate a precise longitudinal movementof the traverse rod 40 relative to the bracket 58.

As shown in FIGS. 1 and 4 of the drawings, a pair of stop members 88 and90 are movably mounted on the traverse rod 40.

The stop member 90 is similar to the stop member 88 and, therefore,construction of these stop members will be described in connection withFIG. 4 of the drawings.

The stop member 90 is provided with a bore portion 92 which is normallyfreely slidable on the traverse rod 40 and disposed at substantiallyright angles to the bore 92 is an internally screw-threaded bore 94 inwhich an externally screwthreaded clamp screw 96 is conforminglyengaged.

A brake shoe 98 is disposed in the bore 94 and engagable with theperiphery of the traverse rod 40, this brake shoe 98 is engaged by theclamp screw 96 for locking the stop member 90 on the traverse rod 40when the clamp screw 96 is tightened.

Thus, the stop members 88 and 90 may be fixed in various positionslongitudinally on the traverse rod 40 and the clamp means 30 as shown inFIG. 1 is provided with respective opposite sides 100 and 102 engagablerespectively with the stop members 88 and 90 generally to limit themovement of the carriage 18 to various predetermined locations fordisposing the plane of the rotary saw blade in desired positions forduplicating various operations as may be desired.

The stop members 88 and 90 may thus be utilized for repeating variousadjustments of the saw blade 10 laterally relative to its axis. However,these stop members 88 and 90 may be removed from the traverse rod orslid to opposite ends thereof out of interference with the clamp means30 of the carriage 18 when desired.

In operation, the carriage 18 may be moved longitudinally relative tothe traverse rod 40 when the screw 46, as shown in FIG. 2 of thedrawings, is released and the carriage 18 may be fixed relative to thetraverse rod 40 when the screw 46, as shown in FIG. 2, is tightened tocause clamping action of the clamp portions 36 and 38 for fixing theclamp means 30 onto the traverse rod 40 and for fixing the traverse rod40 against rotation about its axis. Thus the carriage 18 may be moved toany desired position longitudinally of the radial arm 24 and traverserod 40 when the screw 46 is in release position and this allows therotary or circular saw blade 10, when in rip position as shown in FIG.1, to be moved laterally of its plane of rotation in directionsaccording to the double-ended arrow A. When the blade 10 is thus movedto an approximate desired position the screw 46, by means of knob 48,may be tightened causing the clamp means 30 to fix the carriage inrelation to the traverse rod 40 and to fix the traverse rod 40 againstrotation about its axis. When this is accomplished, fine adjustment ofthe position of the blade 10 relative to its plane of rotation may beaccomplished by rotating the sleeve 56 relative to the bracket 58 and tocause screw-threaded advancement of the traverse rod 40 longitudinallyalong its axis and to thereby concurrently move the carriage 18 to aprecise position for precisely positioning the plane of the saw blade 10relative to the work on the table 28.

It will be noted that when the sleeve 56 is adjusted the dimensionalcalibrations 82 on the knob 70 may be rotated into registry with thepointer 84 as shown in FIG. 3 of the drawings to indicate to theoperator the attainment of a very precise adjustment. However, thecalibrations 82 may not be used since it may be possible visually toadjust the knob 70 until the plane of the circular saw blade 10 is inprecise alignment with a desired precise location as related to the workon the table 28.

The spring 76 acts as a detent means for the sleeve 56 and tends to holdit in fixed position relative to the bracket 58 and to prevent rotationof the sleeve 56 after it has been moved to a precisely adjustedposition. The spring 76 acting against the washer 78 tends to force theenlarged diameter portion 66 of the sleeve 56 against the side 68 of thestationary bracket 58 and thereby frictionally to lock the sleeve 56relative to the bracket 58 and to prevent rotation thereof so that thetraverse rod 40 is maintained in the desired precision adjustedposition.

As shown in FIG. 1 of the drawings, the radial arm saw utilizes aconventional material guide 104 having a side 106 against which materialmay be positioned.

In accordance with the dimension line 108 of FIG. 1 of the drawings, itwill be seen that a plane 110 of the saw blade may be adjusted veryprecisely relative to the line 108 of the guide 104. This may be donewithin thousandths of an inch by means of the adjustments provided bythe sleeve 56 and the screw-threaded portion 52 of the traverse rod 40as hereinbefore described. It will be seen that adjustment of the blade10 may also be accomplished by a precision measuring instrument placedbetween the plane 110 and the side 106 of the member 104.

It will be understood that the foregoing description of the invention isby way of example only and the various ways in which the invention maybe used may vary in accordance with requirements. However, the inventionmay be constructed as disclosed for the purpose of installing it onconventional radial arm saws now in use or the invention may be designedspecifically as a part of new radial arm saws and therefore the specificdetails of the invention may be varied in accordance with requirementsto attain the benefits of the invention in connection with variousradial arm saws.

I claim:

1. In a lateral adjustment means for radial arm saws, the combinationof:

a. an elongated traverse rod;

b. first means for movably supporting said traverse rod on aconventional radial arm saw in substantially parallel disposition to aconvention radial arm thereof;

c. second means for precisely movably adjusting said rod in alongitudinal direction relative to said radial arm and for holding saidrod in precisely adjusted position to said arm; said first meanscomprising external screw threads on said traverse rod; a hollowinternally threaded sleeve conformingly engaging said external screwthreads on said rod; stationary means rotatably mounting said sleeve;and further means restraining axial movement of said sleeve relative tosaid stationary means in two directions, longitudinally relative to therotary axis of said traverse rod;

d. third means adapted to be fixed to a conventional radial arm sawcarriage which is movable longitudinally along said radial arm; and,

e. fourth means for releasably fixing said third means in connectionwith said traverse rod whereby said third means and said carriage may bemoved along said radial arm and relative to said traverse rod toapproximately a desired position, and then said carriage and said thirdmeans may be fixed in approximately said desired position by said fourthmeans and whereby said traverse rod may then be longitudinally adjustedby said second means to a very precise position relative to said firstmeans and said arm and respective saw blade precisely to a desiredposition laterally with respect to the plane of said saw blade.

2. In a lateral adjustment means for radial arm saws, the

combination of:

a. a radial arm saw having an elongated radial arm;

b. a carriage movable longitudinally along said arm;

c. a power saw suspended from said carriage, said power saw adapted topivot on a vertical axis with respect to said carriage and to therebymove from a cross cut position to a rip position;

d. an elongated traverse rod;

e. first means supporting said traverse rod in parallel relation to saidradial arm;

f. second means stationarily mounted with respect to said radial arm andadapted for precisely movably adjusting said rod in a longitudinaldirection relative to said radial arm and for holding said rod inprecisely adjusted position relative to said arm; said first meanscomprising external screw threads on said traverse rod; a hollowinternally threaded sleeve conformingly engaging said external screwthreads on said rod; stationary means rotatably mounting said sleeve;and further means restraining axial movement of said sleeve relative tosaid stationary means in two directions, longitudinally relative to therotary axis of said traverse rod.

3. The invention as defined in claim 1 wherein said second meanscomprises:

a. external screw threads on said traverse rod;

b. a hollow internally screw-threaded sleeve conformingly engaging saidexternal screw threads on said rod;

c. said sleeve rotatably mounted relative to said first means andprecisely restrained in a direction axially relative to said sleeve andsaid rod; said first means comprising a stationary member having firstand second opposite sides and having an opening therein; said sleeverotatably mounted in said opening; said sleeve having a fixed enlargeddiameter structure thereon and rotatably mounted and disposed adjacentsaid stationary member at said first side thereof and thereby axiallyrestrained thereagainst; a compression spring having first and secondends and surrounding said sleeve; a washer disposed between said firstend of said spring and said second side of said stationary member; meansfixed to said sleeve and holding said second end of said springcompressibly against said washer; and manually engageable means securedto said sleeve for manually rotating it.

4. The invention as defined in claim 1 wherein:

a. said third means is freely slidably mounted on said rod;

b. said fourth means comprising manually operable screwthreaded clampmeans adapted to fix said third means on said rod.

5. The invention as defined in claim 1 wherein stop means is movablymounted on said rod and adapted to be fixed to said rod, said stop meansbeing adapted to provide interference stops for said carriage as it ismoved longitudinally along said radial arm and with respect to saidtraverse rod.

6. The invention as defined in claim 1, wherein:

a. said second means comprises external screw threads on said traverserods;

b. a hollow internally screw-threaded sleeve'conformingly engaging saidexternal screw threads on said rod; I

c. said sleeve being rotatably mounted relative to said first means andprecisely restrained in a direction axially relative to said sleeve andsaid rod; and, detent means for holding said sleeve in adjusted positionrelative to said first means and said radial arm; said first meanscomprising a stationary member having first and second opposite sidesand having an opening therein; said sleeve rotatably mounted in saidopening; said sleeve having a fixed enlarged diameter structure thereonand rotatably mounted and disposed adjacent said stationary member atsaid first side thereof and thereby axially restrained thereagainst; acompression spring having first and second ends and surrounding saidsleeve; a washer disposed between said first end of said spring and saidsecond side of said stationary member; means fixed to said sleeve andholding said second end of said spring compressibly against said washer;and manually engageable means secured to said sleeve for manuallyrotating it.

7. The invention a defined in claim 1 wherein:

a. said second means comprises external screw threads on said traverserod;

b. a hollow internally screw-threaded sleeve conformingly engaging saidexternal screw threads on said rod;

c. said sleeve rotatably mounted relative to said first means andprecisely restrained in a direction axially relative to said sleeve andsaid rod;

d. means for holding said sleeve in adjusted position;

e. dimensionally calibrated means on said sleeve;

f. a pointer disposed stationarily relative to said calibrated means.

1. In a lateral adjustment means for radial arm saws, the combinationof: a. an elongated traverse rod; b. first means for movably supportingsaid traverse rod on a conventional radial arm saw in substantiallyparallel disposition to a convention radial arm thereof; c. second meansfor precisely movably adjusting said rod in a longitudinal directionrelative to said radial arm and for holding said rod in preciselyadjusted position to said arm; said first means comprising externalscrew threads on said traverse rod; a hollow internally threaded sleeveconformingly engaging said external screw threads on said rod;stationary means rotatably mounting said sleeve; and further meansrestraining axial movement of said sleeve relative to said stationarymeans in two directions, longitudinally relative to the rotary axis ofsaid traverse rod; d. third means adapted to be fixed to a conventionalradial arm saw carriage which is movable longitudinally along saidradial arm; and, e. fourth means for releasably fixing said third meansin connection with said traverse rod whereby said third means and saidcarriage may be moved along said radial arm and relative to saidtraverse rod to approximately a desired position, and then said carriageand said third means may be fixed in approximately said desired positionby said fourth means and whereby said traverse rod may then belongitudinally adjusted by said second means to a very precise positionrelative to said first means and said arm and respective saw bladeprecisely to a desired position laterally with respect to the plane ofsaid saw blade.
 2. In a lateral adjustment means for radial arm saws,the combination of: a. a radial arm saw having an elongated radial arm;b. a carriage movable longitudinally along said arm; c. a power sawsuspended from said carriage, said power saw adapted to pivot on avertical axis with respect to said carriage and to thereby move from across cut position to a rip position; d. an elongated traverse rod; e.first means supporting said traverse rod in parallel relation to saidradial arm; f. second means stationarily mounted with respect to saidradial arm and adapted for precisely movably adjusting said rod in alongitudinal direction relative to said radial arm and for holding saidrod in precisely adjusted position relative to said arm; said firstmeans comprising external screw threads on said traverse rod; a hollowinternally threaded sleeve conformingly engaging said external screwthreads on said rod; stationary means rotatably mounting said sleeve;and further means restraining axial movement of said sleeve relative tosaid stationary means in two directions, longitudinally relative to therotary axis of said traverse rod.
 3. The invention as defined in claim 1wherein said second means comprises: a. external screw threads on saidtraverse rod; b. a hollow internally screw-threaded sleeve conforminglyengaging said external screw threads on said rod; c. said sleeverotatably mounted relative to said first means and precisely restrainedin a direction axially relative to said sleeve and said rod; said firstmeans comprising a stationary member having first and second oppositesides and having an opening therein; said sleeve rotatably mounted insaid opening; said sleeve having a fixed enlarged diameter structurethereon and rotatably mounted and disposed adjacent said stationarymember at said first side thereof and thereby axially restrainedthereagainst; a compression spring having first and second ends andsurrounding said sleeve; a washer disposed between said first end ofsaid spring and said second side of said stationary member; means fixedto said sleeve and holding said second end of said spring compressiblyagainst said washer; and manually engageable means secured to saidsleeve for manually rotating it.
 4. The invention as defined in claim 1wherein: a. said third means is freely slidably mounted on said rod; b.said fourth means comprising manually operable screw-threaded clampmeans adapted to fix said third means on said rod.
 5. The invention asdefined in claim 1 wherein stop means is movably mounted on said rod andadapted to be fixed to said rod, said stop means being adapted toprovide interference stops for said carriage as it is movedlongitudinally along said radial arm and with respect to said traverserod.
 6. The invention as defined in claim 1, wherein: a. said secondmeans comprises external screw threads on said traverse rods; b. ahollow internally screw-threaded sleeve conformingly engaging saidexternal screw threads on said rod; c. said sleeve being rotatablYmounted relative to said first means and precisely restrained in adirection axially relative to said sleeve and said rod; and, d. detentmeans for holding said sleeve in adjusted position relative to saidfirst means and said radial arm; said first means comprising astationary member having first and second opposite sides and having anopening therein; said sleeve rotatably mounted in said opening; saidsleeve having a fixed enlarged diameter structure thereon and rotatablymounted and disposed adjacent said stationary member at said first sidethereof and thereby axially restrained thereagainst; a compressionspring having first and second ends and surrounding said sleeve; awasher disposed between said first end of said spring and said secondside of said stationary member; means fixed to said sleeve and holdingsaid second end of said spring compressibly against said washer; andmanually engageable means secured to said sleeve for manually rotatingit.
 7. The invention a defined in claim 1 wherein: a. said second meanscomprises external screw threads on said traverse rod; b. a hollowinternally screw-threaded sleeve conformingly engaging said externalscrew threads on said rod; c. said sleeve rotatably mounted relative tosaid first means and precisely restrained in a direction axiallyrelative to said sleeve and said rod; d. means for holding said sleevein adjusted position; e. dimensionally calibrated means on said sleeve;f. a pointer disposed stationarily relative to said calibrated means.